Implemented OpenCV demo to demonstrate video device listing and set up code structure for video

opencv_demo/Makefile

@@ -0,0 +1,7 @@
+CC=gcc
+
+capture_playback: capture_playback.c
+	$(CC) -o capture_playback capture_playback.c -lopencv_core -lopencv_highgui
+
+clean:
+	rm -f capture_playback *.o

opencv_demo/README.md

@@ -0,0 +1 @@
+gcc -o example.exe -I C:/opencv/build/include -L C:/opencv/build/x86/vc12/lib capture_playback.c -lopencv_core2411d -lopencv_highgui2411d -luuid -strmiids -lole32 -loleaut32

opencv_demo/capture_playback.c

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+#include <stdio.h>
+#include <stdlib.h>
+
+#include <opencv2/core/core.hpp>
+#include <opencv2/highgui/highgui.hpp>
+
+#ifdef __linux__
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <linux/videodev2.h>
+#endif /* __linux __ */
+
+#ifdef __WIN32
+#include <windows.h>
+#include <dshow.h>
+
+#pragma comment(lib, "strmiids.lib")
+#endif /* __WIN32 */
+
+#define MAX_DEVICES 32
+
+int main(int argc, char *argv[])
+{
+    const char *device_names[MAX_DEVICES];
+    int amt_cameras = 0;
+    int i = 0;
+
+    #ifdef __linux__
+    // Enumerate video capture devices
+    while(i <= MAX_DEVICES)
+    {
+        int fd;
+        struct v4l2_capability video_cap;
+        char device_address[256];
+        snprintf(device_address, sizeof device_address, "/dev/video%d",i);
+
+        if((fd = open(device_address, O_RDONLY)) == -1) {
+            break;
+        }
+        else {
+            // Query capture device information
+            if(ioctl(fd, VIDIOC_QUERYCAP, &video_cap) == -1)
+                perror("cam_info: Can't get capabilities");
+            else {
+                //printf("Card:\t\t '%s'\n", video_cap.card);
+                int name_length = sizeof(video_cap.card);
+                char* name = (char*)malloc(name_length+1);
+                name = video_cap.card;
+                device_names[i] = name;
+            }
+            close(fd);
+            amt_cameras = i;
+        }
+        ++i;
+    }
+    #endif /* __linux__ */
+    
+    #ifdef __WIN32
+    HRESULT hr;
+    CoInitialize(NULL);
+    ICreateDevEnum *pSysDevEnum = NULL;
+    hr = CoCreateInstance(&CLSID_SystemDeviceEnum, NULL, CLSCTX_INPROC_SERVER, &IID_ICreateDevEnum, (void**)&pSysDevEnum);
+    if(FAILED(hr)) {
+        printf("CoCreateInstance failed()\n");
+    }
+    // Obtain a class enumerator for the video compressor category.
+    IEnumMoniker *pEnumCat = NULL;
+    hr = pSysDevEnum->lpVtbl->CreateClassEnumerator(pSysDevEnum, &CLSID_VideoInputDeviceCategory, &pEnumCat, 0);
+    if(hr != S_OK) {
+        pSysDevEnum->lpVtbl->Release(pSysDevEnum);
+        printf("CreateClassEnumerator failed()\n");
+    }
+
+    IMoniker *pMoniker = NULL;
+
+    ULONG cFetched;
+    while(pEnumCat->lpVtbl->Next(pEnumCat, 1, &pMoniker, &cFetched) == S_OK && i <= MAX_DEVICES) {
+        IPropertyBag *pPropBag;
+        hr = pMoniker->lpVtbl->BindToStorage(pMoniker, 0, 0, &IID_IPropertyBag, (void **)&pPropBag);
+        if(SUCCEEDED(hr)) {
+            // To retrieve the filter's friendly name, do the following:
+            VARIANT varName;
+            VariantInit(&varName);
+            hr = pPropBag->lpVtbl->Read(pPropBag, L"FriendlyName", &varName, 0);
+            if (SUCCEEDED(hr)) {
+                if(varName.vt == VT_BSTR) {
+                    //printf("friendly name: %ls\n", varName.bstrVal);
+                    int name_length = wcslen(varName.bstrVal);
+                    char* name = (char*)malloc(name_length + 1);
+                    wcstombs(name, varName.bstrVal, name_length + 1);
+                    device_names[i] = name;
+                    //free(name);
+                } else {
+                    //printf("unfriendly name\n");
+                    device_names[i] = "Unknown Device";
+                }
+                ++i;
+            }
+            
+            VariantClear(&varName);
+            pPropBag->lpVtbl->Release(pPropBag);
+        }
+        pMoniker->lpVtbl->Release(pMoniker);
+    }
+    amt_cameras = i-1;
+    pEnumCat->lpVtbl->Release(pEnumCat);
+    pSysDevEnum->lpVtbl->Release(pSysDevEnum);
+    
+    #endif /* __WIN32 */
+
+    // TODO: Windows video capture enumeration
+
+    // Obtain user camera selection
+    int select_camera = -1;
+    while(select_camera < 0 || select_camera > amt_cameras || select_camera >= MAX_DEVICES) {
+        printf("Select a camera from %d cameras...\n", amt_cameras+1);
+        int i = 0;
+        // Print all collected devices
+        while(i <= amt_cameras)
+        {
+            printf("%d: %s\n", i, device_names[i]);
+            ++i;
+        }
+        printf("\nCamera #:");
+        scanf(" %d", &select_camera);
+    }
+    printf("\nPress spacebar to exit.\n\n");
+
+    // Initialize window
+    cvNamedWindow("Camera", 1);
+    // Initialize camera
+    CvCapture* capture = cvCreateCameraCapture(select_camera);
+    char key = 0;
+    // Run until spacebar is pressed
+    while(key != 32 && capture != NULL) {
+        // Obtains frame from camera and show it on window
+        IplImage* frame = cvQueryFrame(capture);
+        cvShowImage("Camera", frame);
+        key = cvWaitKey(10);
+    } 
+    
+    // Free device list allocations
+    i = 0;
+    while(i <= amt_cameras)
+    {
+        free(device_names[i]);
+        ++i;
+    }
+    
+    // Collapse camera and window
+    cvReleaseCapture(&capture);
+    cvDestroyWindow("Camera");
+
+    return 0;
+}